Write a function similar to triangle in which each row has a
value which is the square of the row number. Use a while loop.

Write a function similar to triangle that multiplies instead of
adds the values.

Rewrite these two functions recursively. Rewrite these functions
using cond .

Write a function for Texinfo mode that creates an index entry at the
beginning of a paragraph for every `@dfn' within the paragraph.
(In a Texinfo file, `@dfn' marks a definition. For more
information, see
"Indicating Definitions, Commands, etc." in Texinfo, The GNU
Documentation Format.)